Typically, four-wheel jack assemblies adapted for use as above noted are provided with caster wheels which can be swivelled or pivoted in all directions about respective vertical axes, thus enabling the jacks to be moved in any direction. unfortunately, such wheels also have a tendency to swivel on their own accord and independently of each other when floor surface irregularities are encountered, thus tending to make the jacks deviate from their intended path of travel. Furthermore, directional control of the caster wheels is difficult if not impossible unless the motivating force is applied to the jack virtually directly above the wheels.
Jacks of this type are commonly used not only to transport heavy transmissions and the like from one location to another along the shop floor, but also to support and carry such heavy, unwieldy components as they are being unbolted from the underside of the vehicles and subsequently replaced after servicing. The jack must be very precisely located in order to properly receive and support the component as it is released from the truck and, in like fashion, must be very carefully repositioned when the component is reattached because the mounting bolts and their receiving holes require exact alignment before replacement is possible.
Yet achieving the required precise location and maneuvering of such jacks can be a frustrating and time-consuming experience, particularly when it is considered that the mechanic must maneuver the jack with its heavy load in very cramped quarters made even all the more confining because the truck is normally not elevated during service of this type. Consequently, the mechanic finds that he must attempt to precisely manipulate the jack via its long operating handle within a tight space and at a distance fairly remote from the actual load-receiving portion of the jack, making the free-swivelling caster wheels all the more difficult to control as they respond on their own accord to every deviating force applied thereto through surface irregularities and otherwise.